<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div><div><font face="Arial">To all, </font></div><div><font face="Arial"><br></font></div><div><font face="Arial">I have been looking at a way to improve my battery life for my trail traffic counters. I am currently using a linear power supply and with Sleep and other power savings methods, I can easily get a week on battery with 4 AA batteries (my board operates at 3.3V with very low average current and I estimate a 150mA max).</font></div><div><font face="Arial"><br></font></div><div><font face="Arial">However, I want to do better: </font></div><div><font face="Arial"><span class="Apple-tab-span" style="white-space: pre;"> </span>- For the SD Card sensor - to go a week on just three AA cells</font></div><div><font face="Arial"><span class="Apple-tab-span" style="white-space: pre;"> </span>- For the wireless sensor - to go 6 months with a 6V lantern battery</font></div><div><font face="Arial"><br></font></div><div><font face="Arial">I started looking at Texas Instrument’s buck-boost switching power supply chips and using their WeBench tool, designed this circuit.</font></div></div><div><div><font face="Arial"><br></font></div><div><font face="Arial">What is better, TI sent me three of these chips for free!</font></div><div><font face="Arial"><br></font></div><div><font face="Arial">My question is in how I am translating their schematic into an EAGLE file I can ask OSHPark to make for me. The schematic has both Control Ground and Power Ground. And the design report says "Use a common ground node for power ground and a different one for control ground to minimize the effects of ground noise. Connect these ground nodes at any place close to one of the ground pins of the IC.”</font></div><div><font face="Arial"><br></font></div><div><font face="Arial">I decided to use a Sparkfun solder jumper which is normally closed to make the connection between GND and pGND. But do any of you know a better way - or could you take a look at my EAGLE files and tell me if I did this right?</font></div><div><br></div><div><font face="Arial">Here are all the files on drop box - </font><a href="https://www.dropbox.com/sh/9qdzturvffr66do/3QMS0SvYHP">https://www.dropbox.com/sh/9qdzturvffr66do/3QMS0SvYHP</a></div></div><div><div></div><div><font face="Arial"><br></font></div><div><font face="Arial">Thanks for the help. If this works, happy to share the design for those who are looking to get more life out of their batteries.</font></div><div><font face="Arial"><br></font></div><div><font face="Arial">Chip</font></div></div></body></html>